1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * X86 specific Hyper-V initialization code. 4 * 5 * Copyright (C) 2016, Microsoft, Inc. 6 * 7 * Author : K. Y. Srinivasan <kys@microsoft.com> 8 */ 9 10 #include <linux/efi.h> 11 #include <linux/types.h> 12 #include <asm/apic.h> 13 #include <asm/desc.h> 14 #include <asm/hypervisor.h> 15 #include <asm/hyperv-tlfs.h> 16 #include <asm/mshyperv.h> 17 #include <linux/version.h> 18 #include <linux/vmalloc.h> 19 #include <linux/mm.h> 20 #include <linux/hyperv.h> 21 #include <linux/slab.h> 22 #include <linux/cpuhotplug.h> 23 #include <clocksource/hyperv_timer.h> 24 25 void *hv_hypercall_pg; 26 EXPORT_SYMBOL_GPL(hv_hypercall_pg); 27 28 u32 *hv_vp_index; 29 EXPORT_SYMBOL_GPL(hv_vp_index); 30 31 struct hv_vp_assist_page **hv_vp_assist_page; 32 EXPORT_SYMBOL_GPL(hv_vp_assist_page); 33 34 void __percpu **hyperv_pcpu_input_arg; 35 EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg); 36 37 u32 hv_max_vp_index; 38 EXPORT_SYMBOL_GPL(hv_max_vp_index); 39 40 static int hv_cpu_init(unsigned int cpu) 41 { 42 u64 msr_vp_index; 43 struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()]; 44 void **input_arg; 45 struct page *pg; 46 47 input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg); 48 pg = alloc_page(GFP_KERNEL); 49 if (unlikely(!pg)) 50 return -ENOMEM; 51 *input_arg = page_address(pg); 52 53 hv_get_vp_index(msr_vp_index); 54 55 hv_vp_index[smp_processor_id()] = msr_vp_index; 56 57 if (msr_vp_index > hv_max_vp_index) 58 hv_max_vp_index = msr_vp_index; 59 60 if (!hv_vp_assist_page) 61 return 0; 62 63 if (!*hvp) 64 *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL); 65 66 if (*hvp) { 67 u64 val; 68 69 val = vmalloc_to_pfn(*hvp); 70 val = (val << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT) | 71 HV_X64_MSR_VP_ASSIST_PAGE_ENABLE; 72 73 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, val); 74 } 75 76 return 0; 77 } 78 79 static void (*hv_reenlightenment_cb)(void); 80 81 static void hv_reenlightenment_notify(struct work_struct *dummy) 82 { 83 struct hv_tsc_emulation_status emu_status; 84 85 rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status); 86 87 /* Don't issue the callback if TSC accesses are not emulated */ 88 if (hv_reenlightenment_cb && emu_status.inprogress) 89 hv_reenlightenment_cb(); 90 } 91 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify); 92 93 void hyperv_stop_tsc_emulation(void) 94 { 95 u64 freq; 96 struct hv_tsc_emulation_status emu_status; 97 98 rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status); 99 emu_status.inprogress = 0; 100 wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status); 101 102 rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq); 103 tsc_khz = div64_u64(freq, 1000); 104 } 105 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation); 106 107 static inline bool hv_reenlightenment_available(void) 108 { 109 /* 110 * Check for required features and priviliges to make TSC frequency 111 * change notifications work. 112 */ 113 return ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS && 114 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE && 115 ms_hyperv.features & HV_X64_ACCESS_REENLIGHTENMENT; 116 } 117 118 __visible void __irq_entry hyperv_reenlightenment_intr(struct pt_regs *regs) 119 { 120 entering_ack_irq(); 121 122 inc_irq_stat(irq_hv_reenlightenment_count); 123 124 schedule_delayed_work(&hv_reenlightenment_work, HZ/10); 125 126 exiting_irq(); 127 } 128 129 void set_hv_tscchange_cb(void (*cb)(void)) 130 { 131 struct hv_reenlightenment_control re_ctrl = { 132 .vector = HYPERV_REENLIGHTENMENT_VECTOR, 133 .enabled = 1, 134 .target_vp = hv_vp_index[smp_processor_id()] 135 }; 136 struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1}; 137 138 if (!hv_reenlightenment_available()) { 139 pr_warn("Hyper-V: reenlightenment support is unavailable\n"); 140 return; 141 } 142 143 hv_reenlightenment_cb = cb; 144 145 /* Make sure callback is registered before we write to MSRs */ 146 wmb(); 147 148 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); 149 wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl)); 150 } 151 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb); 152 153 void clear_hv_tscchange_cb(void) 154 { 155 struct hv_reenlightenment_control re_ctrl; 156 157 if (!hv_reenlightenment_available()) 158 return; 159 160 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl); 161 re_ctrl.enabled = 0; 162 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl); 163 164 hv_reenlightenment_cb = NULL; 165 } 166 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb); 167 168 static int hv_cpu_die(unsigned int cpu) 169 { 170 struct hv_reenlightenment_control re_ctrl; 171 unsigned int new_cpu; 172 unsigned long flags; 173 void **input_arg; 174 void *input_pg = NULL; 175 176 local_irq_save(flags); 177 input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg); 178 input_pg = *input_arg; 179 *input_arg = NULL; 180 local_irq_restore(flags); 181 free_page((unsigned long)input_pg); 182 183 if (hv_vp_assist_page && hv_vp_assist_page[cpu]) 184 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0); 185 186 if (hv_reenlightenment_cb == NULL) 187 return 0; 188 189 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); 190 if (re_ctrl.target_vp == hv_vp_index[cpu]) { 191 /* Reassign to some other online CPU */ 192 new_cpu = cpumask_any_but(cpu_online_mask, cpu); 193 194 re_ctrl.target_vp = hv_vp_index[new_cpu]; 195 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); 196 } 197 198 return 0; 199 } 200 201 static int __init hv_pci_init(void) 202 { 203 int gen2vm = efi_enabled(EFI_BOOT); 204 205 /* 206 * For Generation-2 VM, we exit from pci_arch_init() by returning 0. 207 * The purpose is to suppress the harmless warning: 208 * "PCI: Fatal: No config space access function found" 209 */ 210 if (gen2vm) 211 return 0; 212 213 /* For Generation-1 VM, we'll proceed in pci_arch_init(). */ 214 return 1; 215 } 216 217 /* 218 * This function is to be invoked early in the boot sequence after the 219 * hypervisor has been detected. 220 * 221 * 1. Setup the hypercall page. 222 * 2. Register Hyper-V specific clocksource. 223 * 3. Setup Hyper-V specific APIC entry points. 224 */ 225 void __init hyperv_init(void) 226 { 227 u64 guest_id, required_msrs; 228 union hv_x64_msr_hypercall_contents hypercall_msr; 229 int cpuhp, i; 230 231 if (x86_hyper_type != X86_HYPER_MS_HYPERV) 232 return; 233 234 /* Absolutely required MSRs */ 235 required_msrs = HV_X64_MSR_HYPERCALL_AVAILABLE | 236 HV_X64_MSR_VP_INDEX_AVAILABLE; 237 238 if ((ms_hyperv.features & required_msrs) != required_msrs) 239 return; 240 241 /* 242 * Allocate the per-CPU state for the hypercall input arg. 243 * If this allocation fails, we will not be able to setup 244 * (per-CPU) hypercall input page and thus this failure is 245 * fatal on Hyper-V. 246 */ 247 hyperv_pcpu_input_arg = alloc_percpu(void *); 248 249 BUG_ON(hyperv_pcpu_input_arg == NULL); 250 251 /* Allocate percpu VP index */ 252 hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index), 253 GFP_KERNEL); 254 if (!hv_vp_index) 255 return; 256 257 for (i = 0; i < num_possible_cpus(); i++) 258 hv_vp_index[i] = VP_INVAL; 259 260 hv_vp_assist_page = kcalloc(num_possible_cpus(), 261 sizeof(*hv_vp_assist_page), GFP_KERNEL); 262 if (!hv_vp_assist_page) { 263 ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED; 264 goto free_vp_index; 265 } 266 267 cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online", 268 hv_cpu_init, hv_cpu_die); 269 if (cpuhp < 0) 270 goto free_vp_assist_page; 271 272 /* 273 * Setup the hypercall page and enable hypercalls. 274 * 1. Register the guest ID 275 * 2. Enable the hypercall and register the hypercall page 276 */ 277 guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0); 278 wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id); 279 280 hv_hypercall_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX); 281 if (hv_hypercall_pg == NULL) { 282 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); 283 goto remove_cpuhp_state; 284 } 285 286 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 287 hypercall_msr.enable = 1; 288 hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg); 289 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 290 291 hv_apic_init(); 292 293 x86_init.pci.arch_init = hv_pci_init; 294 295 /* Register Hyper-V specific clocksource */ 296 hv_init_clocksource(); 297 return; 298 299 remove_cpuhp_state: 300 cpuhp_remove_state(cpuhp); 301 free_vp_assist_page: 302 kfree(hv_vp_assist_page); 303 hv_vp_assist_page = NULL; 304 free_vp_index: 305 kfree(hv_vp_index); 306 hv_vp_index = NULL; 307 } 308 309 /* 310 * This routine is called before kexec/kdump, it does the required cleanup. 311 */ 312 void hyperv_cleanup(void) 313 { 314 union hv_x64_msr_hypercall_contents hypercall_msr; 315 316 /* Reset our OS id */ 317 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); 318 319 /* 320 * Reset hypercall page reference before reset the page, 321 * let hypercall operations fail safely rather than 322 * panic the kernel for using invalid hypercall page 323 */ 324 hv_hypercall_pg = NULL; 325 326 /* Reset the hypercall page */ 327 hypercall_msr.as_uint64 = 0; 328 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 329 330 /* Reset the TSC page */ 331 hypercall_msr.as_uint64 = 0; 332 wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64); 333 } 334 EXPORT_SYMBOL_GPL(hyperv_cleanup); 335 336 void hyperv_report_panic(struct pt_regs *regs, long err) 337 { 338 static bool panic_reported; 339 u64 guest_id; 340 341 /* 342 * We prefer to report panic on 'die' chain as we have proper 343 * registers to report, but if we miss it (e.g. on BUG()) we need 344 * to report it on 'panic'. 345 */ 346 if (panic_reported) 347 return; 348 panic_reported = true; 349 350 rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id); 351 352 wrmsrl(HV_X64_MSR_CRASH_P0, err); 353 wrmsrl(HV_X64_MSR_CRASH_P1, guest_id); 354 wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip); 355 wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax); 356 wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp); 357 358 /* 359 * Let Hyper-V know there is crash data available 360 */ 361 wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY); 362 } 363 EXPORT_SYMBOL_GPL(hyperv_report_panic); 364 365 /** 366 * hyperv_report_panic_msg - report panic message to Hyper-V 367 * @pa: physical address of the panic page containing the message 368 * @size: size of the message in the page 369 */ 370 void hyperv_report_panic_msg(phys_addr_t pa, size_t size) 371 { 372 /* 373 * P3 to contain the physical address of the panic page & P4 to 374 * contain the size of the panic data in that page. Rest of the 375 * registers are no-op when the NOTIFY_MSG flag is set. 376 */ 377 wrmsrl(HV_X64_MSR_CRASH_P0, 0); 378 wrmsrl(HV_X64_MSR_CRASH_P1, 0); 379 wrmsrl(HV_X64_MSR_CRASH_P2, 0); 380 wrmsrl(HV_X64_MSR_CRASH_P3, pa); 381 wrmsrl(HV_X64_MSR_CRASH_P4, size); 382 383 /* 384 * Let Hyper-V know there is crash data available along with 385 * the panic message. 386 */ 387 wrmsrl(HV_X64_MSR_CRASH_CTL, 388 (HV_CRASH_CTL_CRASH_NOTIFY | HV_CRASH_CTL_CRASH_NOTIFY_MSG)); 389 } 390 EXPORT_SYMBOL_GPL(hyperv_report_panic_msg); 391 392 bool hv_is_hyperv_initialized(void) 393 { 394 union hv_x64_msr_hypercall_contents hypercall_msr; 395 396 /* 397 * Ensure that we're really on Hyper-V, and not a KVM or Xen 398 * emulation of Hyper-V 399 */ 400 if (x86_hyper_type != X86_HYPER_MS_HYPERV) 401 return false; 402 403 /* 404 * Verify that earlier initialization succeeded by checking 405 * that the hypercall page is setup 406 */ 407 hypercall_msr.as_uint64 = 0; 408 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 409 410 return hypercall_msr.enable; 411 } 412 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized); 413